iTRAQ-base quantitative proteomic analysis of bulblets development in Lilium davidii var. unicolor and LdGASA plays important roles during plant development

Lilium davidii var. unicolor is an important edible Llilium species in China. In this study, we investigated the regulatory proteins and pathways affecting bulblet development through analyzing the proteomes among three developmental stages using the isobaric tags for relative and absolute quantitation proteomics approach. A total of 4,802 proteins were detected, 529, 735, and 637 proteins were differentially expressed between the 0 d vs 15 d, 15 d vs 30 d, 0 d vs 30 d stages, respectively. The Gene Otology and Kyoto Encyclopedia of Genes and Genomes analysis indicated that the metabolic pathway, biosynthesis of secondary metabolites and microbial metabolism in diverse environments were the most enriched pathways, which may promote energy formation and protein synthesis processes. Starch and sucrose metabolism was vital to Lilium bulblets development, and energy needed was opposite in the early and later stage of lily bulblets development. Many proteins were significantly regulated, among them LdGASA was detected as being extremely differentially expressed. We cloned the full length of LdGASA, analyzed its expression profile during lily bulblet development, and constructed its overexpression vector and transformed into Arabidopsis thaliana. The results showed that the full length of LdGASA was 725 bp, and the CDS sequence was 336 bp, LdGASA was mainly expressed at the morphogenesis and development stages of bulblets, and reached the highest at the basic morphogenesis of bulblets (35 d), Arabidopsis thaliana transformation with LdGASA presented stronger growth. These results not only deepened our understanding of the bulblets proteome, but also uncovered new insights into lily bulblet enlargement.